1. Field of the Invention
The present invention relates to a drive device for electrically winding and rewinding film in a camera.
Conventional film winding and rewinding devices use a one-way clutch to wind and rewind the film by respective forward and reverse rotation of a motor. Control of the normal and reverse rotation of the motor is accomplished by switching a selector switch between the terminals of the motor. This control method, however, requires a switch of a complicated structure with large size contact points to switch a relatively large current (about 1 amp.). For these reasons, the conventional art for controlling the motor rotations has many disadvantages of an electric driving device in a camera requiring a compact structure.
Therefore, an object of the present invention is to provide an electric driving device for a camera in which a semi-conductor switching circuit is combined with a simple switch to overcome the disadvantages of conventional electric driving devices.
According to a feature of the present invention, a drive circuit and a control circuit are provided for the winding operation and the driving circuit is used as a control circuit and the control circuit is used as a drive circuit for the rewinding operation, so as to perform the complicated control with a simple circuit structure.
In an electric drive device in which a high voltage power source is used directly for the rewinding operation so as to achieve high speeds, static electricity formed on the dry film surface may damage the latter.
Therefore, according to a feature the present invention, the rewinding speed is regulated by driving the device at a constant voltage lower than the power source during the rewinding operation so as to prevent the occurrence of static electricity on the film.